Fix the hibernation test_resume's swapfile open mode

PATCH In review Chen Yu 2 participants 4 messages Sep 6, 2023

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Suspend to RAM Hibernation

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Chen Yu

author

2023-09-06 04:18 UTC #0 lore raw

v2 cover Fix the hibernation test_resume's swapfile open mode

Fix the regression brought by
commit 5904de0d735b ("PM: hibernate: Do not get block device exclusively in test_resume mode"), which incorrectly open the swapfile in a wrong mode, and causes unexpected behavior during non-hibernation operation.

Fix it by really disabling exclusive mode under test_resume.

This is the v2 of the fix for a hibernation test_resume swapfile open issue. Chenzhou found that v1 has a warning during the stress test. It was due to broken open mode in swsusp_write(), fixes it in v2.

patch 1 is a renaming of the function parameter, to better reflects the swap device open mode.
patch 2 is to fix the open mode on the swap device.

v1: https://lore.kernel.org/lkml/[email protected]/

Chen Yu (2):
PM: hibernate: Rename the function parameter from snapshot_test to
exclusive
PM: hibernate: Fix the exclusive get block device in test_resume mode

 kernel/power/hibernate.c | 12 ++++++------
 kernel/power/power.h     |  4 ++--
 kernel/power/swap.c      | 14 ++++++++------
 3 files changed, 16 insertions(+), 14 deletions(-)

Signature · 1 line

2.25.1

Chen Yu

author

2023-09-06 04:19 UTC #1 lore raw

PATCH v2 1/2 PM: hibernate: Rename the function parameter from snapshot_test to exclusive

Several functions reply on snapshot_test to decide whether to open the resume device exclusively. However there is no strict connection between the snapshot_test and the open mode. Rename the 'snapshot_test' input parameter to 'exclusive' to better reflect the use case.

No functional change is expected.

Signed-off-by Chen Yu <[email protected]>

---
 kernel/power/power.h |  4 ++--
 kernel/power/swap.c  | 14 ++++++++------
 2 files changed, 10 insertions(+), 8 deletions(-)

kernel/power/power.h +2 -2

index 46eb14dc50c3..a98f95e309a3 100644
@@ -168,11 +168,11 @@ extern int swsusp_swap_in_use(void);
 #define SF_HW_SIG		8
 
 /* kernel/power/hibernate.c */
-int swsusp_check(bool snapshot_test);
+int swsusp_check(bool exclusive);
 extern void swsusp_free(void);
 extern int swsusp_read(unsigned int *flags_p);
 extern int swsusp_write(unsigned int flags);
-void swsusp_close(bool snapshot_test);
+void swsusp_close(bool exclusive);
 #ifdef CONFIG_SUSPEND
 extern int swsusp_unmark(void);
 #endif

kernel/power/swap.c +8 -6

index f6ebcd00c410..74edbce2320b 100644
@@ -1513,12 +1513,13 @@ int swsusp_read(unsigned int *flags_p)
 static void *swsusp_holder;
 
 /**
- *      swsusp_check - Check for swsusp signature in the resume device
+ * swsusp_check - Check for swsusp signature in the resume device
+ * @exclusive: Open the resume device exclusively.
  */
 
-int swsusp_check(bool snapshot_test)
+int swsusp_check(bool exclusive)
 {
-	void *holder = snapshot_test ? &swsusp_holder : NULL;
+	void *holder = exclusive ? &swsusp_holder : NULL;
 	int error;
 
 	hib_resume_bdev = blkdev_get_by_dev(swsusp_resume_device, BLK_OPEN_READ,

@@ -1563,17 +1564,18 @@ int swsusp_check(bool snapshot_test)
 }
 
 /**
- *	swsusp_close - close swap device.
+ * swsusp_close - close swap device.
+ * @exclusive: Close the resume device which is exclusively opened.
  */
 
-void swsusp_close(bool snapshot_test)
+void swsusp_close(bool exclusive)
 {
 	if (IS_ERR(hib_resume_bdev)) {
 		pr_debug("Image device not initialised\n");
 		return;
 	}
 
-	blkdev_put(hib_resume_bdev, snapshot_test ? &swsusp_holder : NULL);
+	blkdev_put(hib_resume_bdev, exclusive ? &swsusp_holder : NULL);
 }
 
 /**

Signature · 1 line

2.25.1

Chen Yu

author

2023-09-06 04:19 UTC #2 lore raw

PATCH v2 2/2 PM: hibernate: Fix the exclusive get block device in test_resume mode

In reply to Chen Yu

commit 5904de0d735b ("PM: hibernate: Do not get block device exclusively in test_resume mode") fixes a hibernation issue under test_resume mode. That commit is supposed to open the block device in non-exclusive mode when in test_resume. However the code did the opposite, which is against its description.

In summary, the swap device is only opened exclusively by swsusp_check() with its corresponding *close(), and must be in non test_resume mode. This is to avoid the race condition that different processes scribble the device at the same time. All the other cases should use non-exclusive mode.

Fix it by really disabling exclusive mode under test_resume.

Fixes 5904de0d735b ("PM: hibernate: Do not get block device exclusively in test_resume mode")

Reported-by [email protected]

Closes https://lore.kernel.org/lkml/[email protected]/ open here

Reported-by Pengfei Xu <[email protected]>

Signed-off-by Chen Yu <[email protected]>

---
 kernel/power/hibernate.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

kernel/power/hibernate.c +6 -6

index 2b4a946a6ff5..8d35b9f9aaa3 100644
@@ -786,9 +786,9 @@ int hibernate(void)
 	unlock_device_hotplug();
 	if (snapshot_test) {
 		pm_pr_dbg("Checking hibernation image\n");
-		error = swsusp_check(snapshot_test);
+		error = swsusp_check(false);
 		if (!error)
-			error = load_image_and_restore(snapshot_test);
+			error = load_image_and_restore(false);
 	}
 	thaw_processes();

@@ -945,14 +945,14 @@ static int software_resume(void)
 	pm_pr_dbg("Looking for hibernation image.\n");
 
 	mutex_lock(&system_transition_mutex);
-	error = swsusp_check(false);
+	error = swsusp_check(true);
 	if (error)
 		goto Unlock;
 
 	/* The snapshot device should not be opened while we're running */
 	if (!hibernate_acquire()) {
 		error = -EBUSY;
-		swsusp_close(false);
+		swsusp_close(true);
 		goto Unlock;
 	}

@@ -973,7 +973,7 @@ static int software_resume(void)
 		goto Close_Finish;
 	}
 
-	error = load_image_and_restore(false);
+	error = load_image_and_restore(true);
 	thaw_processes();
  Finish:
 	pm_notifier_call_chain(PM_POST_RESTORE);

@@ -987,7 +987,7 @@ static int software_resume(void)
 	pm_pr_dbg("Hibernation image not present or could not be loaded.\n");
 	return error;
  Close_Finish:
-	swsusp_close(false);
+	swsusp_close(true);
 	goto Finish;
 }

Signature · 1 line

2.25.1

Feng, ChenzhouX

Tested-by on v2 2/2

2023-09-06 05:27 UTC #3 lore raw

回复: [PATCH v2 2/2] PM: hibernate: Fix the exclusive get block device in test_resume mode

Quoted 26 lines

-----邮件原件-----
发件人: Chen, Yu C <[email protected]>
发送时间: Wednesday, September 6, 2023 12:19
收件人: Rafael J. Wysocki <[email protected]>; Brown, Len <[email protected]>; Pavel Machek <[email protected]>
抄送: [email protected]; [email protected]; Feng, ChenzhouX <[email protected]>; Xu, Pengfei <[email protected]>; Chen, Yu C <[email protected]>; [email protected]
主题: [PATCH v2 2/2] PM: hibernate: Fix the exclusive get block device in test_resume mode
commit 5904de0d735b ("PM: hibernate: Do not get block device exclusively in test_resume mode") fixes a hibernation issue under test_resume mode. That commit is supposed to open the block device in non-exclusive mode when in test_resume. However the code did the opposite, which is against its description.
In summary, the swap device is only opened exclusively by swsusp_check() with its corresponding *close(), and must be in non test_resume mode.
This is to avoid the race condition that different processes scribble the device at the same time. All the other cases should use non-exclusive mode.
Fix it by really disabling exclusive mode under test_resume.

Quoted 7 lines

Fixes 5904de0d735b ("PM: hibernate: Do not get block device exclusively in
test_resume mode")
Reported-by [email protected]
Closes:
https://lore.kernel.org/lkml/[email protected]/
Reported-by Pengfei Xu <[email protected]>
Signed-off-by Chen Yu <[email protected]>

It works on my machine, for the whole series,

Tested-by Chenzhou Feng <[email protected]>

thanks,
Chenzhou